Despite the importance of school connectedness and bullying victimization in students' school burnout, to our knowledge, very few studies have analyzed their reciprocal associations, and most of them have used cross-sectional designs. So, the nature and directions of these relations have not been established yet. The general aim of this study was to address this gap by testing a longitudinal model of the association between the mentioned variables in a group of Italian students. The participants are 363 students from Italian secondary schools (34% females; Mage = 13.35, SD = 1.47), who took part in three waves of data collection. One hundred and eighty-four students attended middle school (45% females; Mage = 12.01, SD = 0.46), and 179 students attended high school (22% females; Mage = 14.62, SD = 0.836). The adolescents filled out a questionnaire containing self-report measurements of studied variables three times, with an interval of 6 months. At both school levels, the results show the reciprocal and longitudinal role of school connectedness in reducing burnout, and of school burnout in reducing the sense of connectedness to school, both directly and indirectly. On the contrary, bullying victimization is not longitudinally associated with school burnout, whereas it negatively predicts the level of students' connectedness to school. The study findings have revealed the importance of considering longitudinal and reciprocal associations among school burnout, connectedness, and bullying victimization, and are discussed referring to their implications for research and intervention efforts aimed at promoting students' school well-being.